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most guys on here that have had there car mapped have then at some point replaced there N75 valve with a new standard (S4) or RS2 type..or even played with the adjuster screw..
now are all standard (new) N75 valves set to the same/spec-boost rate or will the map need tweaking to bring it back to the same state of map that you paid for..

most guys on here that have had there car mapped have then at some point replaced there N75 valve with a new standard (S4) or RS2 type..or even played with the adjuster screw..

WHAT? Who'd do a thing like that??!! Perish the thought!

I think we've had this debate before woody - new N75's come from the factory all set at the same solenoid rate (as near as dammit within manufacturing tolerances can allow i think) - so if you're replacing like for like (i.e. S4 valve for S4 valve) then I doubt the re-map you bought from your tuna has to be tweaked.

but valves do wear and springs if any inside do get weak..

I doubt the re-map you bought from your tuna has to be tweaked.

your theory sounds fishy to me..

S4TAN wrote:

the re-map you bought from your tuna .

Nice

The n75 will over time not preform as well as a new one , i fitted a new one on the 6 and found 9bhp !!! I would recommend fitting a new one before you get a car remapped..

but valves do wear and springs if any inside do get weak..

True - I went along the same thought process as this and replaced mine very soon after finding out what it did ... in my garage I have about 5 N75s - all in various states of "tweakedness" - the one on my car is for an RS2 ...

your theory sounds fishy to me..

Groan!

The n75 will over time not preform as well as a new one , i fitted a new one on the 6 and found 9bhp !!! I would recommend fitting a new one before you get a car remapped..

Agreed - my comment about them being the same was referring to ones that come out of the factory all being the same (within manufacturing tolerances) - if you've got an old one on the car (say been there for several years, or since build) then yes - i'd certainly replace it pre-remap.

pre-remap maybe..but if grizz found 9bhp on a dyno just by replacing his N75 then how much would an S4/RS4 find or even lose..my point i suppose is how big a part does the N75 valve play in mapping a car..should they be replaced as part of the health check or before mapping a car even if the car has a clean bill of health..

That's a very good point Simon. I would say "yes", just to be safe and for the cost involved.

should they be replaced as part of the health check or before mapping a car even if the car has a clean bill of health..

Yep - think you're right woody ... same goes for N249s (a solenoid valve too) ... for those that don't bypass them.

A new N249 and N75 is around £65-£70 for the pair - gotta be worth doing.

i,ll look at priceing a little map kit..new N249'N75 and a pair of 710n's..

Simon, what price can you doing just the N249 and N75 ?

grizz wrote:The n75 will over time not preform as well as a new one , i fitted a new one on the 6 and found 9bhp !!! I would recommend fitting a new one before you get a car remapped..

What do you think causes the deterioration - age or use?

Very low mileage '98 car, you can hear my cogs turning I am sure.

Probably use over age Graham - parts deteriorate/wear I guess and aren't as sharp as they were when new - especially considereing that the N75 is a solenoid valve that opens and closes continuously at varying rates according to the ECU requested boost signals.